Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/lib/src/transcript.dart

Index: sdk/lib/_internal/pub_generated/lib/src/transcript.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/transcript.dart b/sdk/lib/_internal/pub_generated/lib/src/transcript.dart
new file mode 100644
index 0000000000000000000000000000000000000000..38702e135780e89293f80f8f789a4d6cd3e9f5a1
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/transcript.dart
@@ -0,0 +1,30 @@
+library pub.transcript;
+import 'dart:collection';
+class Transcript<T> {
+  final int max;
+  int get discarded => _discarded;
+  int _discarded = 0;
+  final _oldest = new List<T>();
+  final _newest = new Queue<T>();
+  Transcript(this.max);
+  void add(T entry) {
+    if (discarded > 0) {
+      _newest.removeFirst();
+      _discarded++;
+    } else if (_newest.length == max) {
+      while (_newest.length > max ~/ 2) {
+        _oldest.add(_newest.removeFirst());
+      }
+      _newest.removeFirst();
+      _discarded++;
+    }
+    _newest.add(entry);
+  }
+  void forEach(void onEntry(T entry), [void onGap(int)]) {
+    if (_oldest.isNotEmpty) {
+      _oldest.forEach(onEntry);
+      if (onGap != null) onGap(discarded);
+    }
+    _newest.forEach(onEntry);
+  }
+}